DHA Enriched Polyunsaturated Fatty Acid Compositions

ABSTRACT

There is provided a vegetable-based lipid composition comprising very high levels of DHA, together with at least one other long-chain polyunsaturated fatty acid (typically as fatty acid esters). The composition typically contains low levels of EPA and palmitic acid. The composition is obtainable from a single source by conventional processing methods, and has improved stability properties.

FIELD OF THE INVENTION

The embodiments disclosed herein relate to new lipid compositions that are enriched with docosahexaenoic acid. The compositions comprise a mixture of polyunsaturated fatty acids which have a number of health benefits. The compositions may provide nutritional benefits and are potentially obtainable from a single source that is both scalable and sustainable. They also have an enhanced stability to oxidation.

BACKGROUND

Omega-3 long chain polyunsaturated fatty acids (LC-PUFAs) are widely recognised as important compounds for human and animal health. These fatty acids may be obtained from dietary sources or to a lesser extent by conversion of linoleic (LA, 18:2ω-6) or α-linolenic (ALA, 18:3ω-3) fatty acids, all of which are regarded as essential fatty acids in the human diet.

From a nutritional standpoint, the most important omega-3 fatty acids are probably α-linolenic acid, eicosapentaenoic acid (“EPA”; 20:5n-3), and docosahexaenoic acid (“DHA”; 22:6n-3). DHA is a LC-PUFA, which is important for brain and eye development. Ingestion of omega-3 PUFAs may also help to prevent coronary diseases. Medical studies clearly indicate that these fatty acids have beneficial health aspects, such as improved cardiovascular and immune functions and reduction of cancer, diabetes, and high blood pressure. Clinical results have demonstrated that a dietary intake of 5.5 g of omega-3 PUFAs per week may be linked to a 50% reduction in the risk of primary cardiac arrest. Consequently, oil containing omega-3 PUFAs has been in high demand for pharmaceutical and dietetic purposes.

Generally, the oxidative stability of a fatty acid decreases noticeably as the number of carbon-carbon double bonds, or the degree of unsaturation, increases. Unfortunately, ALA, EPA, and DHA are all polyunsaturated fats that tend to oxidise readily. EPA (with 5 carbon-carbon double bonds) is significantly more prone to oxidation than ALA; DHA (with 6 carbon-carbon double bonds) is even more prone to oxidation than EPA. As consequence, increasing the omega-3 content tends to reduce the shelf life of many products. These problems become particularly acute with, oils including significant amounts of EPA or DHA.

US 2015/223483 discloses canola oil-based blends which have improved oxidative stability. The stability is achieved by the addition of one or more additives.

US 2011/0027443 discloses fat and oil compositions containing particular blends of oleic acid, linoleic acid, alpha linolenic acid and LC-PUFAs with an improved flavour profile. US 2004/209953 discloses nutritional products containing predominantly monoglycerides and diglycerides of LC-PUFAs. U.S. Pat. No. 5,130,061 describes the use of transesterification and distillation processes to extract DHA from crude oils. U.S. Pat. No. 9,040,730 describes the purification of lipid mixtures containing PUFAs in order to reduce the quantity of undesired sterols in the composition. In each of these cases, fish or microbial oils are used as the source material from which specific blends are obtained.

International patent application no. WO 2013/185184 discloses processes for producing ethyl esters of polyunsaturated fatty acids.

International patent application no. WO 2015/089587 and US patent application no. US 2015/0166928 discloses plant lipid compositions comprising a mixture of omega-3 and omega-6 fatty acids. Genetically modified canola is described in WO 2017/218969 and WO 2017/219006.

International patent application no. WO2011039776 discloses compositions containing highly pure DHA. US patent application no. US 2011/0033595 discloses products containing DHA and EPA in a high combined proportion.

The listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

DISCLOSURE OF THE INVENTION

According to a first aspect of the invention, there is provided a vegetable-based lipid composition comprising:

(i) docosahexaenoic acid (22:6n-3) in an amount of at least about 86% by weight of the total fatty acid content of the composition; and

(ii) a second polyunsaturated fatty acid in an amount of at least about 3% by weight of the total fatty acid content of the composition, wherein the second polyunsaturated fatty acid is the second most abundant polyunsaturated fatty acid in the composition; wherein the docosahexaenoic acid and the second polyunsaturated fatty acid are each independently provided in the form of a fatty acid, a fatty acid salt, a fatty acid ester or a salt of a fatty acid ester.

Said lipid compositions are referred to herein as the “compositions of the invention”.

The present invention relates to lipid compositions containing high levels of docosahexaenoic acid (DHA), either in the form of a free fatty acid, a salt, an ester or a salt of an ester. These compositions have been found to be obtainable from sustainable sources, such as plant sources. They have also been found to have an improved storage stability profile which is evidenced by a reduction in degradation by oxidation during storage. DHA, in particular, is recognised as an important compound for human and animal health. These compositions can be used in feedstuffs, nutraceuticals, cosmetics and other chemical compositions, and they may be useful as intermediates and active pharmaceutical ingredients.

Fatty acid levels in the compositions of the invention can be determined using routine methods known to those skilled in the art. Such methods include gas chromatography (GC) in conjunction with reference standards, e.g. according to the methods disclosed in the examples. In a particular method, the fatty acids are converted to methyl or ethyl esters before GC analysis. Such techniques are described in the Examples. The peak position in the chromatogram may be used to identify each particular fatty acid, and the area under each peak integrated to determine the amount. As used herein, unless stated to the contrary, the percentage of particular fatty acid in a sample is determined by calculating the area under the curve in the chromatogram for that fatty acid as a percentage of the total area for fatty acids in the chromatogram. This corresponds essentially to a weight percentage (w/w). The identity of fatty acids may be confirmed by GC-MS.

References to docosahexaenoic acid and “DHA” in this context are, unless otherwise specified, references to the ω3 form of docosahexaenoic acid, that is docosahexaenoic acid having a desaturation (carbon-carbon double bond) in the third carbon-carbon bond from the methyl end of the fatty acid. Shorthand forms that may be used interchangeably include “22:6n-3” and “22:6ω-3”.

More generally, the terms “polyunsaturated fatty acid” and “PUFA” refer to a fatty acid which comprises at least two carbon-carbon double bonds. The terms “long-chain polyunsaturated fatty acid” and “LC-PUFA” refer to a fatty acid which comprises at least 20 carbon atoms and at least two carbon-carbon double bonds in its carbon chain, and hence include VLC-PUFAs. As used herein, the terms “very long-chain polyunsaturated fatty acid” and “VLC-PUFA” refer to a fatty acid which comprises at least 22 carbon atoms and at least three carbon-carbon double bonds in its carbon chain. Ordinarily, the number of carbon atoms in the carbon chain of the fatty acid refers to an unbranched carbon chain. If the carbon chain is branched, the number of carbon atoms excludes those in sidegroups.

Long-chain polyunsaturated fatty acids may be ω3 (“omega-3”) fatty acids, that is, fatty acids having a desaturation (carbon-carbon double bond) in the third carbon-carbon bond from the methyl end of the fatty acid. They may alternatively be ω6 (“omega-6”) fatty acids, that is, fatty acids having a desaturation (carbon-carbon double bond) in the sixth carbon-carbon bond from the methyl end of the fatty acid. Whilst other unsaturation patterns may be present, the ω6 and particularly ω3 forms are particularly relevant in the context of the present invention.

The compositions of the invention comprise at least two different polyunsaturated fatty acids, including DHA and at least one other polyunsaturated fatty acid. DHA is the most abundant fatty acid present in the composition (by weight relative to the total fatty acid content of the composition). The second most abundant fatty acid in the composition (by weight relative to the total fatty acid content of the composition) is referred to herein as the “second polyunsaturated fatty acid” or “second PUFA”.

The DHA and second PUFA may each be present in the form of a fatty acid, a fatty acid salt, a fatty acid ester or a salt of a fatty acid ester.

As used herein, the term “fatty acid” refers to a carboxylic acid (or organic acid), often with a long aliphatic tail, either saturated or unsaturated. Typically, fatty acids have a carbon-carbon bonded chain of at least 8 carbon atoms in length, more particularly at least 12 carbons in length. Most naturally occurring fatty acids have an even number of carbon atoms because their biosynthesis involves acetate which has two carbon atoms. The fatty acids may be in a free state (non-esterified), referred to herein as a “free fatty acid”, or in an esterified form such as an alkyl ester, part of a triglyceride, part of a diacylglyceride, part of a monoacylglyceride, acyl-CoA (thio-ester) bound or other bound form, or a mixture thereof. The fatty acid may be esterified as a phospholipid such as a phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylglycerol, phosphatidylinositol or diphosphatidylglycerol forms, though preferably it is esterified as an alkyl ester, especially as an ethyl ester. For the avoidance of doubt, unless otherwise stated, the term “fatty acid” encompasses free fatty acids, fatty acid esters and salts of either of these. Unless otherwise stated, quantitative values associated with particular fatty acids refer to the amount (calculated based on weight) of that fatty acid that is present, irrespective of the form (e.g. free acid or ester) in which it is present.

Each fatty acid in the composition may also be independently provided in the form of a salt of a fatty acid, for example an alkali salt or alkaline earth salt. Particular salts that may be mentioned include lithium salts and calcium salts. Such salts have potential additional medicinal benefits or offer processability improvements. Similarly, a fatty acid ester may be provided in the form of a salt of a fatty acid ester. Any combination of fatty acids in the form of free fatty acids, salts, esters or salts of esters may be present in compositions of the invention. By this, we mean that, for the sake of example, the DHA may be present predominantly as an ethyl ester, the ALA (if present) may be present predominantly as a calcium salt of a methyl ester, and the second PUFA may be present predominantly as a free fatty acid.

“Saturated fatty acids” do not contain any double bonds or other functional groups along the chain. The term “saturated” refers to hydrogen, in that all carbons (apart from the carboxylic acid [—COOH] group) contain as many hydrogens as possible. In other words, the omega (ω) end is attached to three hydrogen atoms (CH₃—) and each carbon within the chain is attached to two hydrogen atoms (—CH₂—). The term “total fatty acid” includes fatty acids in all forms, be they saturated or unsaturated, free acids, esters and/or salts.

The term “about,” as used herein when referring to a measurable value such as an amount of a compound, weight, time, temperature, and the like, refers to variations of 20%, 10%, 5%, 1%, 0.5%, or even 0.1% of the specified amount.

Compositions of the invention that may be mentioned include those that contain a high concentration of omega-3 fatty acids, many of which are so-called “essential fats” that are considered to be particularly important for human health. Omega-3 fatty acids can have beneficial effects on HDL cholesterol levels, support brain development in the young, and have been shown to benefit mental health. These fatty acids are generally considered to be precursors to eicosanoids with anti-inflammatory properties. Particular compositions of the invention that may be mentioned include those in which the total amount of omega-3 polyunsaturated fatty acids in the lipid composition is at least about 90%, such as at least about 95%, by weight of the total fatty acid content of the composition.

Omega-6 fatty acids are also considered to be important for human health. In particular, certain omega-6 fatty acids are “essential fats” necessary for good health but the body is unable to synthesise them. However, omega-6 fats have been shown to be precursors to eicosanoids with more pro-inflammatory properties, and so when too many of these eicosanoids are produced, they can increase inflammation and inflammatory disease. Thus, it may be desirable to minimise the amount of such fatty acids in lipid compositions. It is generally accepted that the ratio of omega-6 to omega-3 fatty acids in the diet should be 4:1 or less. However, the normal western diet typically contains a higher proportion of omega-6 fatty acids. The lipid compositions of the present invention advantageously contain low amounts of omega-6 fatty acids, whilst simultaneously containing high amounts of the more beneficial omega-3 fatty acids. In one embodiment, the total amount of omega-6 polyunsaturated fatty acids in the composition is at most about 5% by weight of the total fatty acid content of the composition. In another embodiment, the ratio of the total weight of omega-3 polyunsaturated fatty acids to the total weight of omega-6 polyunsaturated fatty acids in the composition is at least about 10:1. In a further embodiment, the ratio of the total weight of omega-3 polyunsaturated fatty acids to the total weight of omega-6 polyunsaturated fatty acids in the composition is at least about 20:1.

Lipid compositions containing long chain polyunsaturated fatty acids are typically obtained from marine sources (e.g. fish, crustacea), algal sources, or plant sources (e.g. flax or echium). The starting organic matter is first processed in order to extract the oil (generally referred to as the “crude” oil) contained therein. In the case of plant seeds, for example, the seeds are crushed to release the oil which is then separated from the solid matter by filtration and/or decanting. The crude oils often contain levels of polyunsaturated fatty acids which are too low to be useful (e.g. as nutritional products), so enrichment is required. Where the crude oil is lacking in one or more essential components, it is often common to blend together crude or enriched oils from multiple sources (e.g. from fish and algae) to obtain the desired composition. Alternatively, enrichment may be achieved by processing the crude oil to remove unwanted components (e.g. components which deleteriously affect the product's colour, odour or stability, or unwanted fatty acids), whilst maximising the levels of the desired fatty acid components.

The compositions of the present invention are advantageously obtainable from a single source. The use of a single source facilitates efficient and economic processing of the crude oil and manufacture of the lipid compositions of the invention. By the phrase “obtainable from a single source” (or “obtained from a single source”), we mean that the lipid composition is obtainable from one or more organisms of a single taxonomic class. In a particular embodiment, the lipid composition is not derived from multiple organisms across different taxonomic classes. For example, the lipid compositions may not be blends of oils obtained from a combination of fish and algae, or a combination of fish and plants. Instead, the lipid compositions of the invention (or the “crude” oils from which the compositions can be obtained by enrichment techniques, such as transesterification, distillation and chromatography) are obtainable from a single population of organisms, for example, a single source of plant matter or vegetation. For the avoidance of doubt, the phrase “obtainable from a single source” does not exclude the use of multiple organisms of the same species as a source of the lipid composition or “crude” oil, i.e. the use of multiple fish, algal stocks, plants, or plant seeds that are of the same species. Said multiple organisms are preferably all of the same species, or from the same breeding line, or of the same plant variety, or of the same production stock or batch.

In particular lipid compositions of the invention, the DHA is present in an amount of at least about 87% (such as at least about 88%) by weight of the total fatty acid content of the composition. Further particular compositions that may be mentioned include those which contain DHA in an amount of at least about 90% by weight of the total fatty acid content of the composition. In still further embodiments of the invention, the DHA is present in an amount of up to about 96% (such as up to about 95%) by weight of the total fatty acid content of the composition.

The lipid compositions of the invention have advantageously been found to contain a high level of DHA relative to the amount of EPA present. Therefore, in one embodiment, the weight ratio of docosahexaenoic acid to eicosapentaenoic acid in the lipid compositions is at least about 50:1. In further embodiments, the weight ratio of docosahexaenoic acid to eicosapentaenoic acid in the lipid compositions may be in excess of about 100:1, such as greater than about 30:1, and most particularly greater than about 500:1.

Favourably, the amount of EPA in the compositions may be very low. In particular embodiments, the lipid compositions contain up to about 1%, more particularly up to about 0.5%, EPA by weight of the total fatty acid content of the composition.

The compositions of the invention contain a second polyunsaturated fatty acid in an amount of at least about 3% by weight of the total fatty acid content of the composition. Said second polyunsaturated fatty acid is identifiable as being the second most abundant polyunsaturated fatty acid in the composition. The second PUFA may be any PUFA (or salt, ester or salt of an ester thereof), such as an omega-3 PUFA (e.g. ETA, EPA, SDA or DPA). In particular embodiments said second PUFA is a C:20-24 omega-3 polyunsaturated fatty acid containing at least 4 unsaturations. It is particularly preferred that the second PUFA is eicosatetraenoic acid (ETA; 20:4n-3) (or a salt, ester or salt of an ester thereof).

In particular lipid compositions of the invention, the second PUFA (e.g. ETA) is present in an amount of from about 3% to about 12% by weight of the total fatty acid content of the composition. Further particular compositions that may be mentioned include those which contain the second PUFA (e.g. ETA) in an amount of from about 4% to about 10% (from about 5% to about 8%) by weight of the total fatty acid content of the composition.

In one embodiment, the composition of the invention further contains α-linolenic acid (ALA) in an amount of from about 0.1% to about 4% by weight of the total fatty acid content of the composition. ALA is an essential fat that is important for adequate human or animal health. In further such embodiments, the composition contains ALA in an amount of from about 0.3% to about 4%, more particularly from about 0.5% to about 2%, by weight of the total fatty acid content of the composition.

Therefore, a particular vegetable-based lipid composition of the invention that may be mentioned is one comprising:

(i) docosahexaenoic acid (22:6n-3) in an amount of at least about 86% by weight of the total fatty acid content of the composition;

(ii) a second polyunsaturated fatty acid in an amount of at least about 3% by weight of the total fatty acid content of the composition, wherein the second polyunsaturated fatty acid is the second most abundant polyunsaturated fatty acid in the composition; and

(iii) α-linolenic acid (18:3n-3) in an amount of from about 0.1% to about 4% by weight of the total fatty acid content of the composition;

wherein the docosahexaenoic acid, the second polyunsaturated fatty acid and the α-linolenic acid are each independently provided in the form of a fatty acid, a fatty acid salt, a fatty acid ester or a salt of a fatty acid ester.

The compositions of the invention contain up to about 0.5% palmitic acid (16:0) by weight of the total fatty acid content of the composition. In particular embodiments, the compositions contain up to about 0.1%, more particularly up to about 0.05%, palmitic acid by weight of the total fatty acid content of the composition.

The compositions of the invention may also contain other omega-3 fatty acids (in addition to DHA and the second PUFA) such as docosapentaenoic acid (DPA; 22:5n-3) and/or stearadonic acid (SDA; 18:4n-3). In a particular embodiment, the compositions contain DPA in an amount of at least about 0.1%, particularly at least about 0.2% by weight of the total fatty acid content of the composition. In such embodiments, DPA may be present in an amount of up to about 1%, more particularly up to about 0.5%, by weight of the total fatty acid content of the composition.

Preferences and options for a given aspect, feature or embodiment of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all preferences and options for all other aspects, features and embodiments of the invention. For example, the particular quantities of DHA, the second PUFA and the ALA (if present) indicated in the preceding passages are disclosed in all combinations.

A particular lipid composition that may therefore be mentioned is one which comprises:

(i) docosahexaenoic acid (22:6n-3) in an amount of at least about 86% by weight of the total fatty acid content of the composition;

(ii) eicosatetraenoic acid (20:4n-3) in an amount of at least about 3% by weight of the total fatty acid content of the composition, wherein said eicosatetraenoic acid is the second most abundant polyunsaturated fatty acid in the composition; and

(iii) α-linolenic acid (18:3n-3) in an amount of from about 0.1% to about 4% by weight of the total fatty acid content of the composition;

wherein the docosahexaenoic acid, the eicosatetraenoic acid and the α-linolenic acid are each independently provided in the form of a fatty acid, a fatty acid salt, a fatty acid ester or a salt of a fatty acid ester.

In the compositions of the invention, the DHA, the ALA (if present) and the second PUFA may independently be present be in the form of a fatty acid, a fatty acid salt, a fatty acid ester or a salt of a fatty acid ester. In a particular embodiment, these components each take the same form, for example they may be all in the form of a fatty acid, all in the form of a fatty acid salt, all in the form of a fatty acid ester or all in the form of a salt of a fatty acid ester. Where the components are in the form of a fatty acid salt, ester or salt of an ester, then the components may be in the form of the same salt, ester or salt of the ester. For example, the DHA, the ALA (if present) and the second PUFA may be provided in the form of an ethyl ester of the fatty acid.

In a particular embodiment, the DHA, the ALA (if present) and the second PUFA are independently provided in the form of a salt of a fatty acid ester or, most particularly, in the form of a fatty acid ester. Suitable fatty acid esters forms are known to the skilled person. For example, fatty acid ester forms that are nutritionally acceptable and/or pharmaceutically acceptable include ethyl esters, methyl esters, phospholipids, monoglycerides, diglycerides and triglycerides of fatty acids. Different ester forms may be required depending on the intended use of the lipid composition. For example, triglycerides are particularly suited for use in foods intended for human consumption, especially infant consumption, due in part to the taste and the stability of these ester forms to heat treatment (which may be necessary for such food products). Ethyl esters are particularly suited for use in dietary supplements as these ester forms can be manufactured efficiently and easily, and conversion to a triglyceride form is not necessary. Thus, in a further embodiment, the DHA, the ALA (if present) and the second PUFA are each independently provided in the form of a fatty acid ethyl ester or as part of a triglyceride.

Triglycerides are esters derived from glycerol and three fatty acids. As the present invention concerns blends of fatty acids, the fatty acid components in such triglycerides may be mixed in the corresponding ratios. That is, while a mixture of different triglycerides molecules may be present in a composition, the overall fatty acid profile in the composition is as defined in the claims.

Fatty acid components may alternatively be present in the form of “free” fatty acids, i.e. the —COOH form of the fatty acid. However, in particular compositions of the invention, the compositions contain relatively low levels of fatty acids in this form because they are associated with an unpleasant (often “soapy”) taste, and are less stable than fatty acids that are in an esterified form. Free fatty acids are typically removed from oils and lipid compositions by way of alkali or physical refining, e.g. according to processes discussed elsewhere herein. Thus, in one embodiment, the total free fatty acid content in the lipid compositions is less than 5% (such as less than 3%, particularly less than 2%) by weight of the total fatty acid content of the composition.

The fatty acids in the lipid compositions of the invention are typically linear (i.e. not branched) chain fatty acids. Compositions of the invention that may be mentioned include those which contain very low levels of branched chain fatty acids and their esters such that the composition is essentially free of branched chain fatty acids and branched chain fatty acid esters. By the terms “low levels”, we mean that the composition contains branched chain fatty acids and fatty acid esters in an amount of at most about 0.1% by weight of the total fatty acids of the composition.

The lipid compositions of the invention may also contain other components (e.g. other than fatty acids) that originate from the source material and that are not fully removed during the extraction and enrichment process. The precise identities of those other components will vary greatly depending on the source material. Examples of such other components include phytosterols (i.e. plant sterols and plant stanols) present either as a free sterol or as a sterol ester (such as β-sitosterol, β-sitostanol, Δ5-avenasterol, campesterol, Δ5-stigmasterol, Δ7-stigmasterol and Δ7-avenasterol, cholesterol, brassicasterol, chalinasterol, campesterol, campestanol and eburicol). Other examples include antioxidants, such as tocopherols and tocotrienols. Thus, particular lipid compositions of the invention that may be mentioned include those which contain detectable quantities of one or more phytosterols (such as β-sitosterol). Such sterols may be present at at least about 0.01%, but typically not more than about 1%, by weight of the lipid composition.

The compositions of the present invention are advantageously obtainable from plant sources (“vegetable” sources). By the term “vegetable-based”, we mean that at least 70% by weight of the lipids that are present in the compositions of the invention are obtained from vegetable sources. Vegetable sources include plant sources, particularly crops such as cereals. In at least one embodiment, lipids are obtained from a seed oil crop such as Brassica, for example Brassica napus or Brassica juncea. For the avoidance of doubt, however, it is not essential that the compositions be obtained solely from such sources, that is, a proportion (e.g. at most 30% by weight) of the lipids in the compositions of the invention may be obtained from other sources, including marine (e.g. fish or crustacea) oils, algal oils and combinations thereof. In one example at least 80%, such as at least 90%, by weight of the lipids that are present are obtained from vegetable sources. In particular compositions of the invention, essentially all (i.e. at least 95%, at least 99%, or about 100%) of the lipids are obtained from vegetable sources.

In one embodiment, the compositions of the invention (and the feedstuffs and pharmaceutical compositions defined hereinafter) are not of animal (e.g. marine animal) origin. That is, in such embodiments the lipid compositions do not contain any components that are sourced from animals, such as fish and crustacea. Lipid compositions in which no components are obtained from an animal are believed to be advantageous in terms of lipid content, and a stability profile that can be achieved following standard refinement and/or enrichment procedures.

The use of plants as a lipid or fatty acid source offers a number of advantages. For example, marine sources of oils are known to contain relatively high levels of contaminants (such as mercury, PCBs and fish allergens (e.g. parvalbumins)) which are not found in plant materials. Historic overfishing has also depleted the stocks of fish and crustacea (e.g. krill) such that they are no longer sustainable. The present invention therefore offers a sustainably-sourced polyunsaturated fatty acid oil composition containing relatively low levels of unwanted contaminants.

In a particular embodiment, the composition of the invention is derived from a plant. Plants from which the oils are obtained are typically oilseed crops, such as copra, cottonseed, flax, palm kernel, peanut, rapeseed, soybean and sunflower seed. Compositions obtained exclusively from plants therefore may be referred to as “vegetable” oils or “vegetable lipid compositions”. Suitable plants from which the lipid compositions of the invention may be obtained are known to the skilled person and include Brassica sp., Gossypium hirsutum, Linum usitatissimum, Helianthus sp., Carthamus tinctorius, Glycine max, Zea mays, Arabidopsis thaliana, Sorghum bicolor, Sorghum vulgare, Avena sativa, Trifolium sp., Elaesis guineenis, Nicotiana benthamiana, Hordeum vulgare, Lupinus angustifolius, Oryza sativa, Oryza glaberrima, Camelina sativa, or Crambe abyssinica. A particular plant source that may be mentioned in this respect is Brassica sp.

Suitable sources (including marine, algal and plant sources) may be naturally occurring, or may be genetically modified to enhance their ability to produce long chain polyunsaturated fatty acids. Examples of plant sources that have been genetically modified for this purpose, i.e. which originate from recombinant plant cells, are known to the skilled person and are disclosed in International patent application nos. PCT/AU2013/000639 (published as WO 2013/185184), PCT/AU2014/050433 (published as WO 2015/089587), and PCT/AU2015/050340 (published as WO 2015/196250). Genetically modified canola is described in WO 2017/218969 and WO 2017/219006. The disclosures in all of the publications mentioned herein are incorporated by reference in their entirety.

The lipid compositions of the invention may be obtained directly from a naturally occurring source (e.g. an animal, algae and/or a plant). However, it is typically necessary to processes the oils obtained from naturally occurring sources in order to enrich them. Suitable enrichment processes are exemplified in the Examples.

Suitable sources of lipid compositions of the invention, or “crude” oils which may be blended or enriched to produce those compositions, include marine species, algae and plants. Processes for obtaining oils from marine sources are well-known in the art.

Plant sources (such as oilseed sources) are particularly suited due to the low levels of certain contaminants and superior sustainability, as is discussed above. Plants such as Brassica sp. (e.g. canola) produce seeds which can be processed to obtain oil.

Extraction of Oils/Lipids

Techniques that are routinely practiced in the art can be used to extract, process, and analyse oils produced by plants and seeds. Typically, plant seeds are cooked, pressed, and oil extracted to produce crude oil. That oil may, in turn, be degummed, refined, bleached, and/or deodorised. A combination of degumming, refining, bleaching and deodorising has been found to be particularly effective for preparing DHA-enriched lipid mixtures. Thus, in one embodiment, the lipid composition is obtained from a seed oil that has been degummed, refined, bleached and/or deodorised. However, it is not necessary for the oils to be processed in this way and adequate purification and enrichment may be achieved without these methods.

Generally, techniques for crushing seed are known in the art. For example, oilseeds can be tempered by spraying them with water to raise the moisture content to, e.g., 8.5%, and flaked using a smooth roller with a gap setting of 0.23 mm to 0.27 mm. Depending on the type of seed, water may not be added prior to crushing. Extraction may also be achieved using an extrusion process. The extrusion process may or may not be used in place of flaking, and is sometimes used as an add-on process either before or after screw pressing.

In an embodiment, the majority of the seed oil is released by crushing using a screw press. Solid material expelled from the screw press is then extracted with a solvent, e.g. hexane, using a heat traced column, after which solvent is removed from the extracted oil. Alternatively, crude oil produced by the pressing operation can be passed through a settling tank with a slotted wire drainage top to remove the solids that are expressed with the oil during the pressing operation. The clarified oil can be passed through a plate and frame filter to remove any remaining fine solid particles. If desired, the oil recovered from the extraction process can be combined with the clarified oil to produce a blended crude oil. Once the solvent is stripped from the crude oil, the pressed and extracted portions are combined and subjected to normal oil processing procedures.

Refinement and Purification

As used herein, the term “purified” when used in connection with lipid or oil of the invention typically means that that the extracted lipid or oil has been subjected to one or more processing steps to increase the purity of the lipid/oil component. For example, purification steps may comprise one or more of: degumming, deodorising, decolourising, or drying the extracted oil. However, as used herein, the term “purified” does not include a transesterification process or another process that alters the fatty acid composition of the lipid or oil of the invention so as to increase the DHA content as a percentage of the total fatty acid content. Expressed in other words, the fatty acid composition of the purified lipid or oil is essentially the same as that of the unpurified lipid or oil.

Plant oils may be refined (purified) once extracted from the plant source, using one or more of the following process, and particularly using a combination of degumming, alkali refining, bleaching and deodorisation. Suitable methods are known to those skilled in the art (e.g. those disclosed in WO 2013/185184).

Degumming is an early step in the refining of oils and its primary purpose is the removal of most of the phospholipids from the oil. Addition of ca. 2% of water, typically containing phosphoric acid, at 70 to 80° C. to the crude oil results in the separation of most of the phospholipids accompanied by trace metals and pigments. The insoluble material that is removed is mainly a mixture of phospholipids and triacylglycerols. Degumming can be performed by addition of concentrated phosphoric acid to the crude seedoil to convert non-hydratable phosphatides to a hydratable form, and to chelate minor metals that are present. Gum is separated from the seedoil by centrifugation.

Alkali refining is one of the refining processes for treating crude oil, sometimes also referred to as neutralisation. It usually follows degumming and precedes bleaching. Following degumming, the seedoil can be treated by the addition of a sufficient amount of an alkali solution to titrate all of the free fatty acids and phosphoric acid, and removing the soaps thus formed. Suitable alkaline materials include sodium hydroxide, potassium hydroxide, sodium carbonate, lithium hydroxide, calcium hydroxide, calcium carbonate and ammonium hydroxide. Alkali refining is typically carried out at room temperature and removes the free fatty acid fraction. Soap is removed by centrifugation or by extraction into a solvent for the soap, and the neutralised oil is washed with water. If required, any excess alkali in the oil may be neutralised with a suitable acid such as hydrochloric acid or sulphuric acid.

Bleaching is a refining process in which oils are heated at 90 to 120° C. for 10 to 30 minutes in the presence of a bleaching earth (0.2 to 2.0%) and in the absence of oxygen by operating with nitrogen or steam or in a vacuum. Bleaching is designed to remove unwanted pigments (carotenoids, chlorophyll, etc), and the process also removes oxidation products, trace metals, sulphur compounds and traces of soap.

Deodorisation is a treatment of oils and fats at a high temperature (e.g. ca. 180° C.) and low pressure (0.1 to 1 mm Hg). This is typically achieved by introducing steam into the seedoil at a rate of about 0.1 ml/minute/100 ml of seedoil. After about 30 minutes of sparging, the seedoil is allowed to cool under vacuum. This treatment improves the colour of the seedoil and removes a majority of the volatile substances or odorous compounds, including any remaining free fatty acids, monoacylglycerols and oxidation products.

Winterisation is a process sometimes used in commercial production of oils for the separation of oils and fats into solid (stearin) and liquid (olein) fractions by crystallization at sub-ambient temperatures. It was applied originally to cottonseed oil to produce a solid-free product. It is typically used to decrease the saturated fatty acid content of oils.

Transesterification

Crude oils usually contain the desired fatty acids in the form of triacylglycerols (TAGs). Transesterification is a process that can be used to exchange the fatty acids within and between TAGs or to transfer the fatty acids to another alcohol to form an ester (such as an ethyl ester or a methyl ester). In embodiments of the invention, transesterification is achieved using chemical means, typically involving a strong acid or base as a catalyst. Sodium ethoxide (in ethanol) is an example of a strong base that is used to form fatty acid ethyl esters through transesterification. The process may be performed at ambient temperature or at elevated temperature (e.g. up to about 80° C.).

In other embodiments of the invention, transesterification is achieved using one or more enzymes, particularly lipases that are known to be useful for hydrolysing ester bonds, e.g. in glycerides. The enzyme may be a lipase that is position-specific (sn-1/3 or sn-2 specific) for the fatty acid on the triacylglyceride, or that has a preference for some fatty acids over others. Particular enzymes that may be mentioned include Lipozyme 435 (available from Novozymes NS). The process is typically performed at ambient temperature. The process is typically performed in the presence of an excess quantity of the alcohol corresponding to the desired ester form (e.g. by using ethanol in order to form ethyl esters of the fatty acids).

Distillation

Molecular distillation is an effective method for removing significant quantities of the more volatile components, such as the saturated fatty acids, from crude oils. Distillation is typically performed under reduced pressure, e.g. below about 1 mbar. The temperature and time may then be chosen to achieve an approximately 50:50 split between the distillate and residue after a distillation time of a few (e.g. 1 to 10) hours. Typical distillation temperatures used in the production of the lipid compositions of the present invention are in the region of 120° C. to 180° C., particularly between 145° C. and 160° C.

Multiple distillations may be performed, with each distillation being deemed complete when an approximately 50:50 split between the distillate and residue was achieved. The use of successive distillations reduces the overall yield, however two distillations may produce optimal results.

Chromatography

Chromatography is an effective method for separating the various components of LC-PUFA mixtures. It may be used to increase the concentration of one or more preferred LC-PUFAs within a mixture. Chromatographic separation can be achieved under a variety of conditions, but it typically involves using a stationary bed chromatographic system or a simulated moving bed system.

A stationary bed chromatographic system is based on the following concept: a mixture whose components are to be separated is (normally together with an eluent) caused to percolate through a column containing a packing of a porous material (the stationary phase) exhibiting a high permeability to fluids. The percolation velocity of each component of the mixture depends on the physical properties of that component so that the components exit from the column successively and selectively. Thus, some of the components tend to fix strongly to the stationary phase and thus will be more delayed, whereas others tend to fix weakly and exit from the column after a short while.

A simulated moving bed system consists of a number of individual columns containing adsorbent which are connected together in series and which are operated by periodically shifting the mixture and eluent injection points and also the separated component collection points in the system whereby the overall effect is to simulate the operation of a single column containing a moving bed of the solid adsorbent. Thus, a simulated moving bed system consists of columns which, as in a conventional stationary bed system, contain stationary beds of solid adsorbent through which eluent is passed, but in a simulated moving bed system the operation is such as to simulate a continuous countercurrent moving bed.

Columns used in these processes typically contain silica (or a modified silica) as the basis for the stationary phase. The mobile phase (eluent) is typically a highly polar solvent mixture, often containing one or more protic solvents, such as water, methanol, ethanol, and the like, as well as mixtures thereof. The eluent flow rate may be adjusted by the skilled person to optimise the efficiency of the separation process with slower flow rates generally enhancing the separation of the components and facilitating obtention of compositions containing very high levels of a single fatty acid. Chromatographic separation may be repeated to achieve a similar purity enhancement. Detection methods for LC-PUFAs are known to those skilled in the art, and include UV-vis absorption methods as well as refractive index detection methods.

According to a second aspect of the invention, there is therefore provided a process for producing a lipid composition of the invention, which process comprises providing a mixture of fatty acid ethyl esters; subjecting said mixture to a chromatographic separation process. The present invention also relates to lipid compositions that are obtainable by such processes. Suitable chromatographic separation conditions include those described herein.

For example, particular a particular mobile phase that may be used in the chromatographic separation is a mixture of methanol and water (e.g. 88% methanol/water), though this may be changed (e.g. to increase the methanol content) during the separation process to enhance the efficiency. A particular stationary phase that may be used is a silica-based stationary phase, such as a Deltaprep C18 column. Analytical HPLC, or any other suitable technique known to the person skilled in the art, may be performed on the fractions obtained to identify those that contain high concentrations of DHA and thus contain the lipid compositions of the invention.

In an embodiment of the second aspect of the invention, the mixture of fatty acid ethyl esters is obtained by transesterification and distillation of a vegetable-based lipid oil, e.g. in accordance with any one of the processes hereinbefore described. The vegetable-based lipid oil may be obtained from any of the plants, particularly the oilseeds, disclosed herein or otherwise known in the art. Prior to transesterification and distillation, refinement of the vegetable-based lipid oil using degumming, alkali refinement, bleaching and/or deodorisation may optionally be performed.

Other Enrichment Methods

The lipid compositions of the present invention are useful as active pharmaceutical ingredients (APIs) or as precursors (or “intermediates”) to APIs which may be obtained therefrom by way of further enrichment. Such compositions would be further enriched in the levels of beneficial PUFAs, such as DHA and/or ALA.

The concentration of polyunsaturated fatty acids in an oil can be increased by a variety of methods known in the art, such as, for example, freezing crystallization, complex formation using urea, supercritical fluid extraction and silver ion complexing. Complex formation with urea is a simple and efficient method for reducing the level of saturated and monounsaturated fatty acids in the oil. Initially, the TAGs of the oil are split into their constituent fatty acids, often in the form of fatty acid esters. These free fatty acids or fatty acid esters, which are usually unaltered in fatty acid composition by the treatment, may then be mixed with an ethanolic solution of urea for complex formation. The saturated and monounsaturated fatty acids easily complex with urea and crystallise out on cooling and may subsequently be removed by filtration. The non-urea complexed fraction is thereby enriched with long chain polyunsaturated fatty acids.

Products

The lipid compositions of the present invention are bulk oils. That is, the lipid composition has been separated from the source matter (e.g. plant seeds) from which some or all of the lipid was obtained).

The lipid compositions of the present invention can be used as feedstuffs. That is, the compositions of the invention may be provided in an orally available form. For purposes of the present invention, “feedstuffs” include any food or preparation for human consumption which when taken into the body serves to nourish or build up tissues or supply energy; and/or maintains, restores or supports adequate nutritional status or metabolic function. Feedstuffs include nutritional compositions for babies and/or young children such as, for example, infant formula. In the case of feedstuffs, the fatty acids may be provided in the form of triglycerides in order to further minimise any unpleasant tastes and maximise stability.

Feedstuffs comprise a lipid composition of the invention optionally together with a suitable carrier. The term “carrier” is used in its broadest sense to encompass any component which may or may not have nutritional value. As the skilled person will appreciate, the carrier must be suitable for use (or used in a sufficiently low concentration) in a feedstuff such that it does not have deleterious effect on an organism which consumes the feedstuff.

The feedstuff composition may be in a solid or liquid form. Additionally, the composition may include edible macronutrients, protein, carbohydrate, vitamins, and/or minerals in amounts desired for a particular use as are well-known in the art. The amounts of these ingredients will vary depending on whether the composition is intended for use with normal individuals or for use with individuals having specialised needs, such as individuals suffering from metabolic disorders and the like.

Examples of suitable carriers with nutritional value include macronutrients such as edible fats (e.g. coconut oil, borage oil, fungal oil, black current oil, soy oil, and mono- and diglycerides), carbohydrates (e.g. glucose, edible lactose, and hydrolysed starch) and proteins (e.g. soy proteins, electrodialysed whey, electrodialysed skim milk, milk whey, or the hydrolysates of these proteins).

Vitamins and minerals that may be added to the feedstuff disclosed herein include, for example, calcium, phosphorus, potassium, sodium, chloride, magnesium, manganese, iron, copper, zinc, selenium, iodine, and Vitamins A, E, D, C, and the B complex.

The lipid compositions of the present invention can be used in pharmaceutical compositions. Such pharmaceutical compositions comprise the lipid composition of the invention optionally together with one or more pharmaceutically-acceptable excipients, diluents or carriers, which are known to the skilled person. Suitable excipients, diluents or carriers include phosphate-buffered saline, water, ethanol, polyols, wetting agents or emulsions such as a water/oil emulsion. The composition may be in either a liquid or solid form, including as a solution, suspension, emulsion, oil or powder. For example, the composition may be in the form of a tablet, capsule, encapsulated gel, ingestible liquid (including an oil or solution) or powder, emulsion, or topical ointment or cream. The pharmaceutical composition may also be provided as an intravenous preparation.

Particular forms suitable for feedstuffs and for pharmaceutical compositions include liquid-containing capsules and encapsulated gels.

The lipid compositions of the invention may be mixed with other lipids or lipid mixtures (particularly vegetable-based fatty acid esters and fatty acid ester mixtures) prior to use. The lipid compositions of the invention may be provided together with one or more additional components selected from the group consisting of an antioxidant (e.g. a tocopherol (such as alpha-tocopherol or gamma-tocopherol) or a tocotrienol), a stabiliser, and a surfactant. Alpha-tocopherol and gamma-tocopherol are both naturally occurring components in various plant seed oils, including canola oils.

It may also be desirable to include isotonic agents, for example, sugars, sodium chloride, and the like. Besides such inert diluents, the composition can also include adjuvants, such as wetting agents, emulsifying and suspending agents, sweetening agents, flavouring agents and perfuming agents. Suspensions, in addition to the lipid compositions of the invention, may comprise suspending agents such as ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminium metahydroxide, bentonite, agar-agar, and tragacanth or mixtures of these substances.

Solid dosage forms such as tablets and capsules can be prepared using techniques well known in the art. For example, fatty acids produced in accordance with the methods disclosed herein can be tableted with conventional tablet bases such as lactose, sucrose, and cornstarch in combination with binders such as acacia, cornstarch or gelatin, disintegrating agents such as potato starch or alginic acid, and a lubricant such as stearic acid or magnesium stearate. Capsules can be prepared by incorporating these excipients into a gelatin capsule along with the relevant lipid composition and optionally one or more antioxidants.

Possible routes of administration of the pharmaceutical compositions of the present invention include, for example, enteral (e.g., oral and rectal) and parenteral. For example, a liquid preparation may be administered orally or rectally. Additionally, a homogenous mixture can be completely dispersed in water, admixed under sterile conditions with physiologically acceptable diluents, preservatives, buffers or propellants to form a spray or inhalant.

The lipid compositions of the invention are indicated as pharmaceuticals. According to a further aspect of the invention there is provided a composition of the invention, including any of the pharmaceutical compositions described hereinabove, for use as a pharmaceutical.

Lipid compositions of the invention may provide a number of benefits that are typically associated with long-chain polyunsaturated fatty acids. For example, the lipid compositions of the invention, and the pharmaceutical compositions described hereinabove, may be used in the treatment or prevention of cardiovascular disease, protection against death in patients with cardiovascular disease, reduction of overall serum cholesterol levels, reduction in high BP, increase in HDL:LDL ratio, reduction of triglycerides, or reduction of apolipoprotein-B levels, as may be determined using tests that are well-known to the skilled person. Accordingly, methods of treating (or preventing) the diseases and conditions listed above using the lipid compositions of the invention are also disclosed.

As used herein, the terms “treatment,” “treat,” and “treating” refer to reversing, alleviating, inhibiting the progress of a disease or disorder as described herein, or delaying, eliminating or reducing the incidence or onset of a disorder or disease as described herein, as compared to that which would occur in the absence of the measure taken. As used herein, the terms “prevent”, “prevention” and “preventing” refer to the reduction in the risk of acquiring or developing a given condition, or the reduction or inhibition of the recurrence or said condition in a subject who is not ill.

A typical dosage of a particular fatty acid is from 0.1 mg to 20 g, taken from one to five times per day (up to 100 g daily) and is particularly in the range of from about 10 mg to about 1, 2, 5, or 10 g daily (taken in one or multiple doses). As known in the art, a minimum of about 300 mg/day of fatty acid, especially LC-PUFA, is desirable. However, it will be appreciated that any amount of fatty acid will be beneficial to the subject.

When used as a pharmaceutical composition, the dosage of the lipid composition to be administered to the patient may be determined by one of ordinary skill in the art and depends upon various factors such as weight of the patient, age of the patient, overall health of the patient, past history of the patient, immune status of the patient, etc.

The compositions of the invention are readily obtainable compositions which may have an improved stability profile and which may contain a mixture of fatty acids in which the relative proportions of omega-3 and omega-6 fatty acids are particularly beneficial for human health. Stability may be assessed using a variety of methods known to those skilled in the art. Such methods include the Rancimat method, the assessment of propanal formation (particularly appropriate for omega-3 fatty acids), the assessment of hexanal formation (particularly appropriate for omega-6 fatty acids), the “peroxide value” method (e.g. using AOCS official method Cd 8-53) and the “p-anisidine value” method (e.g. using AOCS official method Cd 18-90). It is shown in the Examples that the compositions of the invention are obtainable from starting mixtures which do not show an enhanced stability profile in comparison to reference blends (the reference blends having a similar composition in terms of the key LC-PUFAs but containing a significant quantity of lipid of animal (fish) origin).

The compositions of the invention may also have the advantage that they may be more efficacious than, be less toxic than, be longer acting than, be more potent than, produce fewer side effects than, be more easily absorbed than, and/or have a better pharmacokinetic profile (e.g. higher oral bioavailability and/or lower clearance) than, and/or have other useful pharmacological, physical, or chemical properties over, lipid compositions known in the prior art.

The invention is illustrated by the following examples in which:

FIG. 1 shows propanal release data for the canola oil and reference oil (following transesterification, distillation and chromatography), demonstrating the improved stability of the canola oil described herein; and

FIG. 2 shows propanal release data for the canola oil and reference oil (following RBD refinement, transesterification, distillation and chromatography), demonstrating the improved stability of the canola oil described herein.

EXAMPLES Example 1—DHA Canola Oil Extraction from Seeds

Canola of a variety disclosed in US patent publication no. US 2018/0016590 A1 was grown as a summer crop. The seed was harvested and then stored at room temperature prior to crushing.

272 kg of the seed was crushed to produce DHA oil using a Kern Kraft KK80 screw press. The expeller collar heater temperature was set to the maximum set temperature on the thermostat. Initial ambient and choke temperature was 20° C. and the choke distance was set at 73.92 mm. The seed was fed with continual oil and meal collection without stopping the expeller till all the seed was crushed.

The speed of rotation of the auger, the temperature of the meal and expelled oil were monitored throughout the pressing. The crush time was 4 hours for 270 kg which is a throughput rate of 67.5 kg/hr. A yield of 87.2 kg (32%) crude oil was obtained. After filtering to remove fines, the yield was 77.2 kg (28%).

Example 2—Reference Blend Oil

Pure fish oil contains low levels of ALA fatty acids and significantly higher levels of EPA and DHA. A reference oil blend (referred to herein as the “crude triglyceride reference blend oil” or similar) was designed to be as similar as possible in composition to the filtered DHA Canola oil obtained in Example 1. This was done by (a) matching the total level of DHA to that in the DHA Canola oil and (b) matching the ratio of DHA/(ALA+EPA). This was achieved by blending a fish oil rich in DHA (tuna), an oil rich in ALA (flaxseed oil) and standard Canola oil. The resulting reference blend oil also has a similar total omega-3 content to the DHA Canola oil.

Example 3—Fatty Acid Compositions of the Crude DHA Canola Oil and Reference Blend

The fatty acid compositions of the filtered crude oil and the reference blend oil were analysed. The results are shown below.

Crude DHA Crude Reference Fatty Acid Canola oil (wt %) oil (wt %) Palmitic C16:0 4.3 9.6 Stearic C18:0 1.9 3.8 Oleic C18:1n9c 39.4 30.6 Cis-vaccenic C18:1n7c 3.6 2.0 Linoleic C18:2n6c 7.8 11.5 GLA C018:3n6 0.1 0.1 ALA C18:3n3 21.9 21.2 Arachidic C20:0 0.7 0.4 SDA C18:4n3 2.2 0.2 Gondoic C20:1n9c 1.4 0.8 Behenic C22:0 0.3 0.2 ETA C20:4n3 1.0 0.1 Erucic C22:1n9c 0.0 0.1 EPA C20:5n3 0.4 1.7 DPA3 C22:5n3 0.9 0.4 DHA C22:6n3 10.2 9.8 Other 4.0 7.6

Example 4—Oil Stability Assessment

A Rancimat stability study was performed using the crude DHA canola oil and reference blend described in Examples 1 and 2, respectively. The method involved testing about 2.5 g of test material using the standard procedures for a Metrohm 743 Rancimat at 90° C.

The table below summarises the results obtained from these oils at 90° C. The experiments were performed in duplicate.

Oil Time DHA Canola oil  7 hrs 29 min  7 hrs 17 min Reference oil 10 hrs 26 min 10 hrs 11 min

The DHA canola oil showed consistently poorer stability than the reference oil.

Example 5—Chemical Trans-Esterification of Crude Canola-DHA Oil

To a dry, nitrogen flushed Buchi CR101 chemreactor fitted with a mechanical stirrer was added absolute ethanol (12.5 L) and the crude triglyceride canola oil (“DHA Canola oil”) obtained in Example 1 (5.00 kg) and the mixture stirred.

To the above mixture was added sodium ethoxide (150 g) which was rinsed into the reactor with further absolute ethanol (2.5 L) and stirring continued for 16 hr at ambient temperature. A ¹H NMR spectrum recorded of a sample taken from the mixture indicated the reaction was complete.

The trans-esterification procedure was performed on 5.22 kg of crude canola-DHA oil. To the resulting crude reaction mixture was added 40-60° C. boiling point petroleum spirits (pet. spirit, 10 L) and water (10 L) and the mixture carefully acidified to pH 7 with 10% hydrochloric acid (870 mL in total required, Merck Universal Indicator strips, pH 0-14) with thorough mixing.

The resulting mixture was allowed to stand in the reactor, after which 2 phases formed. The pet. spirit layer was removed and the aqueous layer further extracted with pet. spirit (3×5 L). The combined pet. spirit layers were returned to the reactor and evaporated in vacuo to low volume (approx. 10 L). The resulting concentrated solution was drained from the reactor, dried over anhydrous magnesium sulphate (approx. 1 kg), filtered and concentrated in vacuo to give a yellow oil (5.13 kg).

Example 6—Chemical Trans-Esterification of Crude Reference Blend Oil

To a dry, nitrogen flushed Buchi CR101 chemreactor fitted with a mechanical stirrer was added absolute ethanol (12.5 L) and the crude triglyceride reference blend oil obtained according to Example 2 (5.00 kg) and the mixture stirred.

To the above mixture was added sodium ethoxide (150 g) which was rinsed into the reactor with further absolute ethanol (2.5 L) and stirring continued for 16 hr at ambient temperature. A ¹H NMR spectrum recorded of a sample indicated little or no reaction had taken place. Further sodium ethoxide (57 g) was added to the mixture and stirring continued.

After an additional 5 hrs, a ¹H NMR spectrum of a sample indicated the reaction was 75% complete. Further sodium ethoxide (60 mL of a 21% solution in ethanol) was added to the mixture and stirring continued for 3 days, after which time the reaction was complete.

Example Product Isolation from Crude Reference Blend Chemical Trans-Esterification

The trans-esterification procedure was performed on 5.17 kg of crude reference blend oil. To the resulting crude reaction mixture was added pet. spirit (15 L) and water (3.3 L) and the mixture carefully acidified to pH 7 with 10% hydrochloric acid (910 mL in total required) with thorough mixing.

The resulting mixture was allowed to stand in the reactor, after which 2 phases formed. The pet. spirit layer was removed and the aqueous layer further extracted with pet. spirit (2×7.5 L). The combined pet. spirit layers were returned to the reactor and evaporated in vacuo to low volume (approx. 10 L). The resulting concentrated solution was drained from the reactor, dried over anhydrous magnesium sulphate (approx. 1 kg), filtered and concentrated in vacuo to give a yellow oil (5.39 kg).

Example 7—Distillation of Transesterified Canola Oils

Standard Procedure for the Removal of More Volatile Components of Fatty Acid Ethyl Esters (FAEE) Mixtures by Vacuum Distillation

The crude fatty acid ethyl esters (FAEE) from the crude canola-DHA (obtained in Example 5) were subjected to distillation under the following conditions. Separation by distillation was achieved by passing the trans-esterified crude oil through a Pope 2 inch (50 mm) wiped film still under vacuum equipped with 2×1000 ml collection flasks collecting the distillate and residue. Each was analysed for fatty acid composition.

Vacuum was supplied by an Edwards 3 rotary pump and the vacuum measured by an ebro vacumeter VM2000.

The oil was fed into the still by a Cole-Palmer Instrument Company easy-load II peristaltic pump at 4 mL/min with the still motor set to 325 rpm with water condenser used to condense the distillate. The feed was continued until such time as one or other of the receiver flasks was full.

Crude canola-DHA FAEE was distilled under these conditions with the heater bands initially set to 147° C. The objective was to obtain a 50:50 split of distillate:residue. During the first 30-45 minutes of the experiment, the temperature of the heater bands was increased to 154° C. to increase the proportion of the oil that distilled and the still then allowed to equilibrate. After half an hour, the temperature of the heater bands was adjusted over half an hour down to 149° C. The remainder of the distillation took place at 149° C. The total time of distillation was 350 minutes. A portion of the residue from the above distillation was again subjected to the removal of more volatile components by distillation under the standard conditions with the temperature of the heater bands set to 149° C. The total time of distillation was 95 minutes.

Distillation Feed Distillate Residue First 1395.4 g 699.5 g 690.5 g Second 376.3 g 211.7 g 160.3 g

Example 8—Distillation of Transesterified Crude Reference Blend-Derived FAEE

The crude fatty acid ethyl esters (FAEE) from the crude reference blend (obtained in Example 6) were subjected to distillation under the same conditions as shown in the preceding Example.

Crude reference blend FAEE was distilled under these standard conditions with the heater bands initially set to 152° C. The objective was to obtain a 50:50 split of distillate:residue. After 20 minutes the temperature of the heater bands was set to 154° C. to increase the flow of distillate. After a further hour the heater bands temperature was adjusted to 153° C. and then 152° C. over the next hour. For the last hour of the distillation the heater bands temperature was set to 153° C. The total time of distillation was 380 minutes. The residue from the above distillation was again subjected to the removal of more volatile components by distillation under the standard conditions. The objective was to obtain a 50:50 split of distillate:residue. The distillation was mostly performed with the heater bands set to 150-151° C. The total time of distillation was 195 minutes.

Distillation Feed Distillate Residue First 1515.7 g 729.6 g 775.1 g Second 768.5 g 399.7 g 363.3 g

Example 9—Chromatographic Separation of Canola-Derived FAEE

Preparative HPLC

The fatty acid ethyl esters (FAEE) obtained in Example 7 (i.e. that had been obtained from the crude canola-DHA and processed using transesterification and distillation) were subjected to chromatographic separation under the following conditions. A preparative HPLC system comprising a Waters Prep 4000 system, Rheodyne injector with 10 ml loop, 300×40 mm Deltaprep C18 column, Waters 2487 dual wavelength detector and chart recorder was equilibrated with 88% methanol/water mobile phase at 70 mL/min. The detector was set to 215 nm and 2.0 absorbance units full scale and the chart run at 6 cm/hr.

1.0 g of FAEE oil was dissolved in a minimum amount of 88% methanol/water and injected onto the column via the Rheodyne injector. Approximately 250 mL fractions were collected once the solvent front appeared after around 7 minutes.

A total of 43 fractions were collected over 140 minutes. After 85 minutes the mobile phase was changed to 90% methanol/water. After 105 minutes the mobile phase was changed to 94% methanol/water. After 110 minutes the mobile phase was changed to 100% methanol. After the final fractions were collected the column was washed for a further 1 hour with 100% methanol at 70 ml/min. Analytical HPLC was performed on all the fractions, and the fractions containing predominantly DHA were combined (yield: 22%).

Analytical HPLC

An HPLC system comprising a Waters 600E pump controller, 717 autosampler, 2996 photodiode array detector and 2414 refractive index detector was used for sample analysis. The analysis was performed on a 150×4.6 mm Alltima C18 column using either isocratic 90% methanol/water or 95% methanol/water at 1.0 mL/min as mobile phase. Data collection and processing was performed in Waters Empower 3 software.

Example 10—Chromatographic Separation of Reference Blend-Derived FAEE

The distilled fatty acid ethyl esters (FAEE) of the reference blend (obtained in Example 8) were subjected to chromatographic separation under the same conditions as shown in the preceding Example.

A total of 43 fractions were collected over 130 minutes. After 75 minutes the mobile phase was changed to 90% methanol/water. After 95 minutes the mobile phase was changed to 95% methanol/water. After 110 minutes the mobile phase was changed to 100% MeOH. After the final fractions were collected the column was washed for a further 1 hour with 100% MeOH at 70 mL/min. Analytical HPLC was performed on all the fractions, and the fractions containing predominantly DHA were combined (yield: approx. 20%).

Example 11—Fatty Acid Composition Analysis for the Enriched Oils

The fatty acid compositions of the products obtained in Examples 9 and 10 were analysed. The results are shown below.

DHA Canola oil Reference oil Fatty Acid (wt %) (Example 9) (wt %) (Example 10) Palmitic C16:0 0.00 0.00 Stearic C18:0 0.00 0.00 Oleic C18:1n9c 0.00 0.02 Cis-vaccenic C18:1n7c 0.00 0.00 Linoleic C18:2n6c 0.60 1.76 GLA C18:3n6 0.01 0.00 ALA C18:3n3 0.71 1.89 Arachidic C20:0 0.03 0.02 SDA C18:4n3 0.00 0.00 Gondoic C20:1n9c 0.00 0.00 Behenic C22:0 0.06 0.00 ETA C20:4n3 5.30 0.70 Erucic C22:1n9c 0.00 0.00 EPA C20:5n3 0.02 0.14 DPA3 C22:5n3 0.27 0.19 DHA C22:6n3 92.62 90.25 Other 0.39 5.04

Example 12—Oil Stability Assessment

Headspace GC-MS Stability Trial

Headspace analysis was conducted on the enriched products described above to assess the quantities of propanal that are released under specific conditional. Increased levels of propanal release demonstrate reduced stability for the test material.

SPME (Solid-Phase Microextraction) Method:

Selected 65 μm PDMS/DVB StableFlex fiber (Supelco fiber kit 57284-u)

Fibers were conditioned for 10 mins prior to use at 250° C. in a Triplus RSH conditioning station

Samples were incubated at 40° C. for 1 min prior to extraction.

Extracted for 1 min from Headspace vial

Expected to be a good general method capable of capturing a wide range of volatile components.

GC Method:

Thermo Scientific TRACE 1310 GC

Thermo Scientific TR-DIOXIN 5MS column, 0.25 mm internal diameter, 30 m film 0.1 μm

Split injection 250° C. Split 83, 1.2 ml He/min

GC Ramp: 40° C. 1 min to 100 at 5° C./min, then to 300° C. at 50° C./min

A generic MS specific column with good synergy for headspace analysis was used. A slow initial temperature ramp was employed to maximise separation of volatiles before ramping up to maximum to maintain column performance. Split injections were employed to avoid the requirement for cryogenic cooling of the inlet and enhance column resolution.

Separation of the standards was hampered by some peak overlap but could still be accommodated in the quantitation. 3 standard calibration results (0.1, 0.01 and 0.01%), the molecular ion m/z 56 was employed for detection of propanal. The base peak at m/z 58 is used to detect hexanal.

MS Method:

Thermo Scientific DFS high resolution GC-MS

Low resolution (1000), full scan 35-350 Da at 0.5 s/scan

Standards:—Propanal and Hexanal standard dilutions were made into DHA Canola Ethyl esters supplied. These Standard mixtures were then added at a volume of 540 μl to 20 ml headspace vials.

Full scan was employed, allowing the monitoring of all evolved products rather than specific molecules.

Headspace Stability Results:

The table below summarises the results obtained from the canola oil obtained in Example 9 and the reference oil obtained in Example 10 from T=0 to 2 days. Test samples were held during this period at ambient temperature on a light box and under fluorescent tube lighting. The m/z 58 molecular ion was analysed, and the mass chromatogram clearly shows emergence of propanal at RT 1.37 mins. Propanal development is quantified in the table below, and the data are shown in FIG. 1. The DHA canola oil released substantially lower amounts of propanal demonstrating the improved stability of the canola oil as compared to the reference.

Time point (days) 0 2 DHA Canola oil (ppm propanal) 823.974 1392.985 Reference oil (ppm propanal) 1149.539 2318.177

The DHA Canola oil showed superior stability to oxidation compared with the reference oil.

Example 13—Refinement of DHA Canola Oil

A portion of the canola oil obtained in Example 1 was refined prior to undergoing further enrichment. The refinement process involved degumming, alkali refinement, bleaching and deodorisation.

Acid Degumming

Degumming is the removal of non-hydratable and hydratable phosphatides from the oil. The dried crude oil obtained in Example 1 was heated to 53±2° C. and 0.2% of a 50% citric acid solution was added. After approximately 30 minutes of mixing, 2.0% of heated (53±2° C.) softened water was added and mixed for approximately 30 minutes. The oil was heated to 67±3° C. during the hold and then centrifuged.

Acid Pretreat/Refining

Refining is the removal of free fatty acids following their saponification with caustic to make them water-soluble and their subsequent removal by centrifugation. An acid pretreatment step was used to continue the hydration of the phosphatides. The degummed oil was heated to 65±5° C. and 0.1% of 85% phosphoric acid added, and mixed for a total of 30 minutes. After the acid addition and hold time, 20 Be′ (Baumé; 14.4%, w/w) sodium hydroxide was added to neutralise the free fatty acids plus a 0.05% (w/w) excess. The caustic and oil were then mixed for an additional 15 minutes. The oil was heated to 62±2° C. during the 15-minute hold, and then the oil was centrifuged.

Trisyl Silica Treatment

Trisyl silica treatment was performed for the further removal of soaps, to levels compatible with bleaching. Trisyl pretreatment was combined with the bleaching step. The refined oil was heated to 68±5° C. and treated with 0.3% of Trisyl 300. The oil/Trisyl was mixed for approximately 15 minutes, and then bleaching was continued.

Bleaching

Refined oil was treated with adsorptive clay for the removal of peroxides, phosphatides, colour bodies and traces of soap. An acid pretreatment step was used to continue the hydration of the phosphatides. The Trisyl pretreated oil was mixed with 0.2% (w/w) of a 50% citric acid solution. After 15 minutes of mixing, 2% (w/w) of Tonsil Supreme 126 FF bleaching clay was added. The mixture was then heated to 90±2° C. under vacuum and held for approximately 30 minutes. The oil was cooled to 60±2° C., vacuum broken with nitrogen, 1.0 kg of filter aid added and filtered. Pressure Vessel: 500 L Cherry-Burrell pressure vessel, steam or cooling water jacket, all 316 stainless construction with impeller and baffles for mixing, mfg's serial #E-227-94. Filter Press: 24″ Polypropylene Sperry Filter Press, capacity 4.8 cu ft filter, paper and cloth supports were used.

Deodorizing

The bleached oil was subjected to sparging with steam at high temperature and low pressure to remove odoriferous components, flavour components, and additional free fatty acids. Colour is also reduced by heat bleaching at elevated temperatures. The half of the bleached oil was deodorised at 180±2° C. for 60 min with 1% sparge steam and Fatty Acid Composition (FAC) was monitored. Deodoriser Vessel (OD4): 400 L Coppersmithing vacuum rated vessel, steam or cooling water jacket, all 316 stainless construction. A slight decrease of DHA level was observed at 180° C. for 60 min hold. Then another trial was conducted at 180° C. for 30 min hold. The product was packaged under nitrogen in 20-L plastic HDPE pails and stored in a cooler at 4° C.

Example 14—Refinement of Original Reference Blend Oil

A portion of the reference blend described in Example 2 was refined prior to undergoing further enrichment. In the refinement process the reference blend was subjected to refinement under the same conditions as shown in the preceding Example.

Example 15—Fatty Acid Compositions of the RBD Crude DHA Canola Oil and Reference Blend

The fatty acid compositions of the RBD filtered crude oil (of Example 13) and the RBD reference blend oil (of Example 14) were analysed. The results are shown below.

Crude DHA Crude Reference Fatty Acid Canola oil (wt %) oil (wt %) Palmitic C16:0 4.23 9.22 Stearic C18:0 2.52 3.89 Oleic C18:1n9c 42.90 31.62 Cis-vaccenic C18:1n7c 3.01 1.96 Linoleic C18:2n6c 7.15 12.18 GLA C18:3n6 0.54 0.00 ALA C18:3n3 19.95 22.51 Arachidic C20:0 0.72 0.38 SDA C18:4n3 2.25 0.17 Gondoic C20:1n9c 1.28 0.71 Behenic C22:0 0.31 0.22 ETA C20:4n3 1.08 0.00 Erucic C22:1n9c 0.00 0.00 EPA C20:5n3 0.47 1.67 DPA3 C22:5n3 0.96 0.41 DHA C22:6n3 9.33 9.20 Other 3.32 5.86

References to “RBD” in connection with the Examples (and the accompanying figures) mean that the product in question was obtained directly or indirectly from the “refined” products of either Example 13 (for Canola oils) and Example 14 (for reference blends).

Example 16—Chemical Trans-Esterification of RBD Canola-DHA Oil

To a dry, nitrogen flushed Buchi CR101 chemreactor fitted with a mechanical stirrer was added absolute ethanol (12.5 L) and the refined (“RBD”) triglyceride canola-DHA oil obtained in Example 13 (5.00 kg) and the mixture stirred.

To the above mixture was added sodium ethoxide (150 g) which was rinsed into the reactor with further absolute ethanol (2.5 L) and stirring continued for 16 hr at ambient temperature. A ¹H NMR spectrum recorded of a sample taken from the mixture indicated the reaction was complete.

The trans-esterification procedure was performed on approx. 5 kg of RBD canola-DHA oil. To the resulting crude reaction mixture was added 40-60° C. boiling point petroleum spirits (pet. spirit, 10 L) and water (10 L) and the mixture carefully acidified to pH 7 with 10% hydrochloric acid (870 mL in total required, Merck Universal Indicator strips, pH 0-14) with thorough mixing.

The resulting mixture was allowed to stand in the reactor, after which 2 phases formed. The pet. spirit layer was removed and the aqueous layer further extracted with pet. spirit (3×5 L). The combined pet. spirit layers were returned to the reactor and evaporated in vacuo to low volume (approx. 10 L). The resulting concentrated solution was drained from the reactor, dried over anhydrous magnesium sulphate (approx. 1 kg), filtered and concentrated in vacuo to give a light pale yellow oil (yield: 99%).

Example 17—Chemical Trans-Esterification of RBD Reference Blend Oil

To a dry, nitrogen flushed Buchi CR101 chemreactor fitted with a mechanical stirrer was added absolute ethanol (12.5 L) and the RBD triglyceride reference blend oil obtained according to Example 14 (approx. 5 kg) and the mixture stirred.

To the above mixture was added sodium ethoxide (150 g) which was rinsed into the reactor with further absolute ethanol (2.5 L) and stirring continued for 16 hr at ambient temperature. A ¹H NMR spectrum recorded of a sample indicated little or no reaction had taken place. Further sodium ethoxide (57 g) was added to the mixture and stirring continued.

After an additional 5 hrs, a ¹H NMR spectrum of a sample indicated the reaction was 75% complete. Further sodium ethoxide (60 mL of a 21% solution in ethanol) was added to the mixture and stirring continued for 3 days, after which time the reaction was complete.

Example Product Isolation from RBD Reference Blend Chemical Trans-Esterification

The trans-esterification procedure was performed on approx. 5 kg of RBD reference blend oil. To the resulting crude reaction mixture was added pet. spirit (15 L) and water (3.3 L) and the mixture carefully acidified to pH 7 with 10% hydrochloric acid (910 mL in total required) with thorough mixing.

The resulting mixture was allowed to stand in the reactor, after which 2 phases formed. The pet. spirit layer was removed and the aqueous layer further extracted with pet. spirit (2×7.5 L). The combined pet. spirit layers were returned to the reactor and evaporated in vacuo to low volume (approx. 10 L). The resulting concentrated solution was drained from the reactor, dried over anhydrous magnesium sulphate (approx. 1 kg), filtered and concentrated in vacuo to give a light pale yellow oil (yield: 99%).

Example 18—Distillation of Transesterified RBD Canola Oils

Standard Procedure for the Removal of More Volatile Components of Fatty Acid Ethyl Esters (FAEE) Mixtures by Vacuum Distillation

The fatty acid ethyl esters (FAEE) from the RBD canola-DHA (obtained in Example 16) were subjected to distillation under the following conditions. Separation by distillation was achieved by passing the trans-esterified crude oil through a Pope 2 inch (50 mm) wiped film still under vacuum equipped with 2×1000 ml collection flasks collecting the distillate and residue. Each was analysed for fatty acid composition.

Vacuum was supplied by an Edwards 3 rotary pump and the vacuum measured by an ebro vacumeter VM2000.

The oil was fed into the still by a Cole-Palmer Instrument Company easy-load II peristaltic pump at 4 mL/min with the still motor set to 325 rpm with water condenser used to condense the distillate. The feed was continued until such time as one or other of the receiver flasks was full.

RBD canola-DHA FAEE was distilled under these conditions with the heater bands initially set to 152° C. to obtain a 50:50 split of distillate:residue. A portion of the residue from this distillation was again subjected to the removal of more volatile components by distillation under the standard conditions with the temperature of the heater bands set to 152° C. The total time of distillation was approx. 90 minutes.

Distillation Feed Distillate Residue First 1596.6 729.9 855.9 Second 851.3 503.5 343.1

Example 19—Distillation of Transesterified RBD Reference Blend-Derived FAEE

The fatty acid ethyl esters (FAEE) from the RBD reference blend (obtained in Example 17) were subjected to distillation under the same conditions as shown in the preceding Example.

RBD reference blend FAEE was distilled under these standard conditions with the heater bands initially set to 152° C. to obtain a 50:50 split of distillate:residue. The residue from this distillation was again subjected to the removal of more volatile components by distillation under the standard conditions. The objective was to obtain a 50:50 split of distillate:residue. The distillation was mostly performed with the heater bands set to 152° C. The total time of distillation was approx. 200 minutes.

Distillation Feed Distillate Residue First 1195.1 674.7 504.6 Second 496.4 297.2 197.4

Example 20—Chromatographic Separation of RBD Canola-Derived FAEE

The fatty acid ethyl esters (FAEE) obtained in Example 18 (i.e. that had been obtained from the RBD canola-DHA and processed using transesterification and distillation) were subjected to chromatographic separation under the following conditions. A preparative HPLC system comprising a Waters Prep 4000 system, Rheodyne injector with 10 ml loop, 300×40 mm Deltaprep C18 column, Waters 2487 dual wavelength detector and chart recorder was equilibrated with 88% methanol/water mobile phase at 70 mL/min. The detector was set to 215 nm and 2.0 absorbance units full scale and the chart run at 6 cm/hr.

1.0 g of FAEE oil was dissolved in a minimum amount of 88% methanol/water and injected onto the column via the Rheodyne injector. Approximately 250 mL fractions were collected once the solvent front appeared after around 7 minutes.

Analytical HPLC was performed on all the fractions, and the fractions containing predominantly DHA were combined (yield: approx. 20%).

Example 21—Chromatographic Separation of RBD Reference Blend-Derived FAEE

The distilled fatty acid ethyl esters (FAEE) of the RBD reference blend (obtained in Example 19) were subjected to chromatographic separation under the same conditions as shown in the preceding Example.

Analytical HPLC was performed on all the fractions, and the fractions containing predominantly DHA were combined (yield: approx. 20%).

Example 22—Fatty Acid Composition Analysis for the Enriched RBD Oils

The fatty acid compositions of the products obtained in Examples 20 and 21 were analysed. The results are shown below.

DHA Canola oil Reference oil Fatty Acid (wt %) (Example 20) (wt %) (Example 21) Palmitic C16:0 0.02 0.00 Stearic C18:0 0.02 0.00 Oleic C18:1n9c 0.00 0.00 Cis-vaccenic C18:1n7c 0.00 0.00 Linoleic C18:2n6c 2.40 7.28 GLA C18:3n6 0.06 0.00 ALA C18:3n3 1.02 1.19 Arachidic C20:0 0.03 0.00 SDA C18:4n3 0.03 0.00 Gondoic C20:1n9c 0.00 0.00 C20:4n6 0.00 3.66 Behenic C22:0 0.05 0.00 ETA C20:4n3 6.76 0.64 Erucic C22:1n9c 0.00 0.00 EPA C20:5n3 0.04 0.00 DPA3 C22:5n3 0.32 0.00 DHA C22:6n3 88.27 81.12 Other 0.99 6.11

Example 23—Oil Stability Assessment

Headspace analysis was conducted on the enriched products described in Examples 20 and 21 accordance with the method described in Example 12.

The table below summarises the results obtained from the RBD canola oil obtained in Example 20 and the RBD reference oil obtained in Example 21 from T=0 to 2 days. Test samples were held during this period at ambient temperature on a light box and under fluorescent tube lighting. The m/z 58 molecular ion was analysed, and the mass chromatogram clearly shows emergence of propanal at RT 1.37 mins. Propanal development is quantified in the table below, and the data are shown in FIG. 2. The DHA canola oil released substantially lower amounts of propanal demonstrating the improved stability of the canola oil as compared to the reference.

Time point (days) 0 2 DHA Canola oil (ppm propanal) 0.000 706.232 Reference oil (ppm propanal) 1449.640 1582.057

The DHA Canola oil showed superior stability to oxidation compared with the reference oil. 

1. A vegetable-based lipid composition comprising: (i) docosahexaenoic acid (22:6n-3) in an amount of at least 86% by weight of the total fatty acid content of the composition; and (ii) a second polyunsaturated fatty acid in an amount of at least about 3% by weight of the total fatty acid content of the composition, wherein the second polyunsaturated fatty acid is the second most abundant polyunsaturated fatty acid in the composition; and wherein the docosahexaenoic acid and the second polyunsaturated fatty acid are each independently provided in the form of a fatty acid, a fatty acid salt, a fatty acid ester or a salt of a fatty acid ester.
 2. The lipid composition of claim 1, wherein docosahexaenoic acid (22:6n-3) is present in an amount of about 87% to about 96% by weight of the total fatty acid content of the composition.
 3. The lipid composition of claim 1, wherein the weight ratio of docosahexaenoic acid to eicosapentaenoic acid in the composition is at least 50:1.
 4. The lipid composition of claim 1, wherein the second polyunsaturated fatty acid is a C:20-24 omega-3 polyunsaturated fatty acid containing at least four unsaturations.
 5. The lipid composition of claim 1, wherein the second polyunsaturated fatty acid is present in an amount of from about 3% to about 12% by weight of the total fatty acid content of the composition.
 6. The lipid composition of claim 1, wherein the vegetable-based lipid composition further comprises α-linolenic acid (18:3n-3) in an amount of from about 0.1% to about 4% by weight of the total fatty acid content of the composition.
 7. The lipid composition of claim 1, wherein the docosahexaenoic acid, the second polyunsaturated fatty acid and the α-linolenic acid (if present) are each independently provided in the form of a fatty acid ester or a salt of a fatty acid ester, such as in the form of a fatty acid ethyl ester or as part of a triglyceride.
 8. The lipid composition of claim 1, wherein the amount of palmitic acid in the composition is less than 0.5% by weight of the total fatty acid content of the composition.
 9. The lipid composition of claim 1, wherein the lipid composition is derived from a single source.
 10. The lipid composition of claim 1, wherein the lipid composition is derived from a plant.
 11. The lipid composition of claim 10, wherein the plant is an oilseed selected from Brassica sp., Gossypium hirsutum, Linum usitatissimum, Helianthus sp., Carthamus tinctorius, Glycine max, Zea mays, Arabidopsis thaliana, Sorghum bicolor, Sorghum vulgare, Avena sativa, Trifolium sp., Elaesis guineensis, Nicotiana benthamiana, Hordeum vulgare, Lupinus angustifolius, Oryza sativa, Oryza glaberrima, Camelina sativa, or Crambe abyssinica.
 12. The lipid composition of claim 11, wherein the lipid composition is obtained from a seed oil that has been degummed, refined, bleached and/or deodorised.
 13. The lipid composition of claim 1, wherein the composition is provided in the form of a tablet, capsule, encapsulated gel, ingestible liquid or powder, emulsion, or a topical ointment or cream.
 14. The lipid composition of claim 1, further comprising one or more additional components selected from the group consisting of an antioxidant, a stabiliser and a surfactant.
 15. The lipid composition of claim 1 for use in the treatment or prevention of cardiovascular disease, protection against death in patients with cardiovascular disease, reduction of overall serum cholesterol levels, reduction in high blood pressure, increase in HDL:LDL ratio, reduction of triglycerides, or reduction of apolipoprotein-B levels.
 16. A method for producing the lipid composition of claim 1, comprising providing a mixture of fatty acid ethyl esters, and subjecting said mixture to a chromatographic separation process, optionally wherein the mixture of fatty acid ethyl esters is obtained by transesterification and distillation of a vegetable-based lipid oil.
 17. The lipid composition of claim 6, wherein the vegetable-based lipid composition comprises α-linolenic acid (18:3n-3) in an amount of from about 0.5% to about 2% by weight of the total fatty acid content of the composition. 